Pneumatic, photoelectric, and ultrasonic systems have been used for guiding material webs by edge detection or line detection. Photoelectric based systems, for example using optical sensors or infrared sensors, have been used to guide material webs based on features of the material web, such as an edge, an aspect of a material web at a given point on the material, or a printed graphic running longitudinally along the material web. Most sensors detect the web or its features by transmitting a signal and comparing a received signal through open atmosphere in relation to a received signal which has been passed through or interrupted by a web.
C shape sensors are common in web edge detection where the web passes through a gap in the C shape. Sensors are often housed in arms of the C extending at least partially across the web. The sensors may be divided between transmitter and receiver elements. The gap of the C shape sensors extend between the arms and may limit acceptable deviations in the web plane of the traveling web while passing through the C shape sensor. In order to overcome this limitation, C shape sensors may be mounted on or connected to an articulable element, known as a moving sensor guide that allows the C shape sensors to move in response to changes in the width of the material web. In addition, rollers may be employed, such as fixed support bars, close to the C shape sensors enabling better control over the web plane and enabling use of C shape sensors using smaller gaps. A plurality of C shape sensors have been used to guide a single material web, with sensors on either side of the material web, to simultaneously perform edge detection on opposing edges of the material web.
C shape sensors may be used in ultrasonic guiding systems, for example as described in U.S. Pat. No. 7,415,881. C shape sensors are also used in photoelectric systems as described in U.S. Pat. No. 4,291,825 that uses infrared sensing devices to perform web edge sensing to guide the material web.
Line sensors may be used which scan graphical patterns on the web, without performing edge detection, for guiding the material web. Line sensors may capture images and guide the material web based on a comparison of the images and the location of the graphical patterns with a stored set point. Line sensors may have a horizontal field of view that spans a portion or the entirety of the material web between opposing edges. However, the line sensors have a field of view in the web direction of travel that is limited to one pixel and encompasses no more than 5-7 microns of the web in the web direction of travel. Other sensors used in web guiding may include laser curtain sensors, ragged edge sensors, fiber optics sensors, raised feature sensors, capacitance or inductance sensors, and mechanical paddle or finger sensors.
Visual inspection systems for providing quality assurance to moving webs of material currently exist. One visual inspection system is sold under the trademark InPrint™ by Fife Corporation, the assignee of the present patent application. This visual inspection system provides quality assurance by allowing direct, live image viewing of a moving web. In particular, this visual inspection system captures images of a moving web at 10 images/second and compares the captured images to a reference image of the web to detect deviations of the captured image from the reference image. When deviations are detected, the visual inspection system sounds an alarm, and/or directs a particular product to an appropriate location to be manually inspected.
Web handling systems exist to control the tension in a web of material. The tension in the web is detected by a load cell bearing on the web of material, and the tension is controlled by a brake or clutch system that can vary the rate of movement of a roller for feeding and/or retrieving of the web of material.
Natural interaction sensors use depth sensors which respond to emitted radiation, such as infrared (IR) frequency wavelengths of light to measure distances between an object and the sensor. Further natural interaction sensors may also employ audio and optical sensors to combine image data, sound data, and distance data to provide three dimensional interactions between an object and a computer system. Commercially available natural interaction sensors are sold under a variety of trade names including KINECT™, LEAP™, and XTION PRO LIVE™. However, natural interaction sensors have not previously been used in web handling systems.
There is a need for a web handling system capable of guiding and/or tensioning material webs based on one or a combination of factors including a location of one web edge or multiple web edges, while enabling improved quality inspection of the web in an automated setting.